Mandrels for use in seating rolls of material, in particular for seating paper rolls, are generally known in the paper and printing industry. Such mandrels are employed at the roll changers of web-fed rotary printing presses to rotatably seat or support the rolls of material, from which the paper to be imprinted is drawn off, during operation of the web-fed rotary printing press. A so-called flying roll change is often performed at such roll changers. In this connection, a flying roll change means that gluing of a leading end of a fresh roll, to a tensioned web of an exhausting paper web, can be performed while the tensioned, exhausting paper web continues its running off. Only fractions of seconds are available for performing such a flying roll change, during which time the tension, tensile stress and shearing strain must be exactly maintained.
To be able to perform a flying roll change, the fresh paper web roll must be accelerated in such a way that its circumferential speed corresponds exactly to the linear speed of the paper web which is running off. The torque required for accelerating the fresh roll of the web of material is transmitted to that roll by appropriately suitable drive systems. In this connection, so-called belt-drive systems are known, for example, wherein drive belts are brought into contact with the circumference of the fresh roll. These belt-drive systems accelerate the fresh roll by the use of an appropriate frictional connection between the belts and the roll outer surface. Moreover, so-called cardan drives are known, wherein the required drive torque is transmitted to receiver elements, which receiver elements come into contact with the roll of material on both of its sides.
A mandrel is known, for example, from EP 0 453 800 B1. With this mandrel, radially drivable, spreading cheeks are provided at the receiver element which cheeks, after the receiver element has been arranged in a core of the roll of material, can be moved apart to make a frictional connection between the roll of material and the mandrel. It is not inconceivable, in connection with such mandrels with radially spreading cheeks that, because of the high inherent weight of the roll and thus because of the resultant high moments of acceleration, the roll of material will slide over, or with respect to the clamping cheeks during roll acceleration or braking. This undesirable slippage can cause irregularities in the movement progress of the roll. Furthermore, the interior surface of the core of the roll of material can be damaged by such a sliding of the spreading cheeks with respect to the core, so that a secure fastening of the roll of material on the mandrel is no longer provided.
DD 82615 describes a clamping device for winding tubes. Several clamping pins, with knife-like cutting edges, are pressed into the winding tube.
DE 28 32 361 A1, DE 21 00 746 A, DE-PS 972 578, GB 2 293 225 A and DE 73 17 470 U all disclose mandrels with engagement elements which engage the web of material by positive contact.